An end-to-end polychromatic Fresnel propagation model of GPI

Abstract

The Gemini Planet Imager (GPI) is a future high-order coronagraphic adaptive optics system optimized for the search and analysis of Jupiter-like exoplanets around nearby young 10-1000Myr stars. In this paper, an on-axis Fresnel wavefront propagation model of GPI is presented. The main goal of this work is to confirm that the current GPI design will reach its 10^-7 contrast requirement. The model, assembled using the PROPER IDL library, is used to properly simulate out-of-pupil-plane and finite size optics. A spectral data cube at GPI spectral resolution R=45 in H-band is obtained to estimate the GPI contrast as a function of wavelength. This cube is then used to evaluate the speckle suppression performance of the Simultaneous Spectral Differential Imaging (SSDI) technique. It is shown that GPI should achieve a photon noise limited 10^-7 contrast when using a simple SSDI post-processing on an H=5 star and a 1h observing sequence. Finally, a long exposure data cube is obtained by combining the speckle contributions of an average atmosphere and GPI optics. That final long-exposure contrast as a function of wavelength can be used to estimate the GPI exoplanet characterization accuracy, and to evaluate, using Monte-Carlo simulations, the expected exoplanet survey performance.